Various systems have been suggested to date to enable the locating and tracking of stolen or missing vehicles. For example, U.S. Pat. No. 5,895,436 (SAVOIE) discloses a vehicle tracking system using the existing cellular network, whereas U.S. Pat. No. 5,225,842 (BROWN) discloses a vehicle tracking system employing global positioning system (GPS) satellites for position/location determination.
However, such prior art tracking systems are very dependent upon third party infrastructures to determine location information, which is disadvantageous for many reasons.
For example, tracking systems that use the cellular network are limited by constraints such as having to locate the missing vehicle through relative signal strength methods between cellular base stations. These systems also require several back and forth signalling transmissions between the location transceiver mounted in the vehicle and the base stations of the cellular network. One disadvantage of such tracking systems is that the cell distribution is not the same throughout the network and the accuracy of the tracking may vary depending on the number of base stations available at any site.
In the case of GPS tracking systems, the signals that are used are even weaker than in cellular networks requiring antennas with a clear view to the sky, also GPS does not work indoors.
There is therefore a need for a vehicle and/or asset tracking tracking system that is not dependent on the infrastructure of the existing wireless systems to obtain the location information of a missing vehicle or asset.
Furthermore, in this same field of vehicle security, it is known to use wireless remote cut-off modules to disable critical components in a vehicle such as fuel pumps, ignition, starter, fuel injection, etc., to prevent engine starting by unauthorized users.
The main disadvantage of present cut-off modules is the fact that since they must be wired to the main control unit, the wiring is easy to follow. Therefore they can be located and bypassed with little effort.